Whether you're a beginner bird watcher or an experienced veteran, you're always within reach of a good pair of binoculars. And a lot of birders will agree that they are always in search of the absolute best pair of binoculars in the world. There are a lot of options out there, but what is the best for you? Only you can decide that, but we may be able to help. This guide is designed to help new birders understand how binoculars work, and give experienced bird watchers some insight on the more advanced aspects of their binoculars.
The first thing you'll notice about any pair of binoculars is the numbers in their name, such as 10x25, 8x32, 15x70, etc. These numbers are used to describe the binocular's optical configuration, which is an indicator of what they can be used for.
The first number is the power of the binocular, more commonly referred to as the magnification. This number indicates how many times bigger the image seen through the binocular is when compared to the naked eye. So, a 7x binocular will make objects in the distance appear about 7 times larger than they would if you were looking without binoculars.
The second number is the size of the objective lenses of the binocular in millimeters (these are the lenses that are farthest away from your eye when looking through a pair of binoculars). So, for example, a 10x50 binocular will magnify your view ten times, and has objective lenses that are 50mm wide.
So what do the numbers actually mean?
Well, it can get complicated. Since your eyes are different from everybody else's eyes, what you actually "see" through a pair of binoculars will vary slightly. But, there are some basic rules that can be followed when we look strictly at those numbers. Generally, a smaller magnification and larger objective size is more desirable. But there are limitations to this, which is why every power/objective configuration has its advantages and disadvantages.
Let's discuss power (magnification). A higher magnification has an obvious advantage: it makes everything you look at appear to be closer, which is what a binocular is designed to do. A lot of people assume that a higher magnification is obviously better because of this. Unfortunately, the disadvantages to higher mangification make a binocular with high power useless in most birdwatching situations. First, higher mangification usually means a narrow field of view, which can make tracking a moving bird difficult. If you are unfamiliar with field of view, we'll talk more about that later. Second, a high power 12x binocular not only makes birds appear 12 times closer, it amplifies accidental movement from your arms by 12 times as well. It can be very difficult to track a bird when trying to overcorrect for unsteady arms.
Now let's discuss objective lens diameter. Objective lenses can also be referred to as aperture, meaning the opening that light travels through to get through the rest of the binocular. Either term is correct. At face value, a larger objective lens usually means that it will collect more light, at the expense of size and weight. Collecting light is important because it will allow you to make out more detail in situations where little light is available, such as cloudy days or early morning/late evening. So, the goal is to get the largest objective size possible that is still comfortable.
Why are these factors important? Birding is all about being able to easily track fast moving birds, while seeing as much detail as possible, and remaining comfortable while doing it.
Field of View
Field of view is a term used to describe the visible area at a given distance, commonly measured at 1000 yards and degrees. When you see a binocular with a field of view of 300 feet at 1000 yards, that means that you can see a horizontal area about the size of an NFL football field at a distance of 1000 yards. A wider field of view is usually more desirable, because it is another binocular quality that makes it easier to track a fast moving bird. Magnification, objective lens size, and several other factors work together to determine what a binocular's field of view will be, and two nearly identical binoculars can have very different fields of view.
What magnification is best?
This question can really only be answered by you, because your preference will dictate which magnification you are most comfortable with. However, it's safe to assume that 7x, 8x, and 9x magnifications are some of the most popular for serious bird watchers. These are just enough power to see fine detail at a distance most birds will be encountered, while not being so powerful that they become difficult to use. A magnification of 10x is also somewhat popular, but is on the higher end of what most birders would consider acceptable, because stability and field of view become limiting factors.
However, most birders are known to have several pairs of binoculars with a wide range of mangification, so they are always prepared for any situation.
Clarity and sharpness
You'll see these terms quite a bit when reading reviews about binoculars for birdwatching, along with a few others. All the quirks and qualities of a binocular work together (and sometimes against each other) to produce the image you see when looking through the eyepieces. Here's a quick run down of what these terms mean.
Waterproofing and fogproofing
All binoculars that are waterproof are fogproof, and vice-versa. Waterproofing and fogproofing is accomplished during the manufacturing process by pumping all of the air out of the body of the binocular, and replacing it with an inert gas, thereby removing all moisture from inside the optical bodies. Since there is no moisture, the inside of the lenses can never fog. This is very important to bird watchers who pursue the hobby in all types of weather, because a pair of binoculars that fogs is useless. Keep in mind that this only refers to the fogging on the inside of the lenses; there is no way to prevent fogging on the outside due to body heat and condensation.
Waterproofing and fogproofing isn't absolutely necessary. Every birder should have an inexpensive pair of binoculars within reach, and they don't necessarily have to be fully waterproof. The tradeoff is cost, because inexpensive binoculars will not usually be fogproof. But, if you are going to spend over $100 on a pair of birdwatching binoculars, make sure the pair you choose is waterproof. There is no reason a binocular at or above that price should not be able to stand up to adverse weather conditions.
What binoculars do I need for birdwatching?
That really is the question, isn't it? Below are several common binocular configurations that work best for bird watching.